1. The Technical Field
The present invention is directed to a therapeutic support apparatus, system and method that may be used for mitigating the formation of and/or assisting in the treatment of decubitus ulcers (also sometimes referred to as “pressure ulcers”).
2. The Prior Art
Decubitus ulcers can result from excessive and unrelieved pressure applied to a person's body. For example, decubitus ulcers can result from a person lying on a bed, mattress, pad or other support surface in one position for an extended period of time, during which the interface pressure between the support surface and the user's body exceeds the vascular occlusion threshold. The vascular occlusion threshold is the maximum pressure that may be applied to a person's skin by a supporting surface without cutting off subcutaneous or capillary blood flow in the area of the person's body in contact with the supporting surface. Put another way, subcutaneous blood flow is likely to be cut off in areas of contact between a user and a supporting surface if the pressure applied to the person by the support surface exceeds the vascular occlusion threshold. The vascular occlusion threshold is generally deemed to be about 28-32 mm Hg (about 0.5 psi) but can be lower, particularly in users having low blood pressure.
Excessive and unrelieved heat and moisture about the skin and shear forces applied to the skin also can contribute to the formation of decubitus ulcers. Such shear forces can pinch off blood vessels, particularly perforator vessels perpendicular to the skin, and, therefore, inhibit subcutaneous blood flow.
Traditional methods and apparatus for mitigating the formation of and assisting in the treatment of decubitus ulcers involve distributing the user's weight over a relatively large area (typically as large an area as possible) of a support surface so that the interface pressure between the user's body and the support surface generally remains below the vascular occlusion threshold (such techniques sometimes are referred to as “redistribution”). Such methods may further involve alternating areas of the support surface over which the user's weight is distributed.
For example, redistribution techniques sometimes involve the use of relatively thick air mattresses having two alternately inflatable compartments that are operated at low internal pressures (typically 0.5-1.0 psi or less). Operation at such low pressures allows the user's body weight to be distributed over a relatively large area such that a relatively low interface pressure may be realized. One approach uses an air mattress having two alternately inflatable compartments, each defining a plurality of relatively large, generally circular air cells operated at pressures of about 25 mm Hg (about 0.5 psi) that distribute the user's weight over a relatively large surface area. The air cells are about 5 inches in diameter, and the air mattress has a thickness of about 2.5 inches or greater when inflated. Another approach involves a support pad having smaller, more-closely spaced, and elongated air cells. The air cells and fluid channels connecting them are formed into the surface of the pad.
Redistribution techniques have not proven to be entirely satisfactory. Such techniques do not necessarily provide for maintenance of adequate subcutaneous blood flow or adequate relief from shear and environmental effects.